Reaction products of multiaziridino compounds and hydrogen sulfide

ABSTRACT

Novel adducts of multiaziridino compounds are prepared by reacting H2S with multiaziridino compounds. The reaction products, which contain secondary amino and thio groups, may be used to form adhesives, particularly with epoxy compounds, and metal-to-metal laminates.

United States Patent 1 Uelzmann et al.

3,725,460 Apr. 3, 1973 REACTION PRODUCTS OF MULTIAZIRIDINO COMPOUNDS ANDHYDROGEN SULFIDE Inventors: Heinz Uelz mann, Cuyahoga Falls; David C.Hidinger, Jr., Akron, both of Ohio Assignee: The General Tire 8: RubberCompany, Akron, Ohio Filed: Nov. 3, 1969 Appl. No.: 873,683

Related U.S. Application Data Division of Ser. No. 637,352, May 10,1967, Pat. No.

U.S. Cl. 260/470, 260/239 E, 260/402.5, 260/481 R, 260/5708 R,260/570.9, 260/583 EE Int. Cl ..C07c 149/42 Field of Search ..260/471 C,2 EN, 470, 5 70.8 R

References Cited OTHER PUBLICATIONS lwakura et al., Journal of OrganicChemistry, Vol. 26 (l96l) pgs. 4384 to 4385 relied on.

Primary Examiner-Lorraine A. Weinberger Assistant Examiner-L. ArnoldThaxton Attorney-Kemon, Palmer & Estabrook, Frank C. Rote, Jr. andDenbigh S. Matthews 57 ABSTRACT 2 Claims, No Drawings REACTION PRODUCTSOF MULTIAZIRIDINO COMPOUNDS AND HYDROGEN SULFIDE This application is adivision of copending U. S. Patent application Ser. No. 637,352 filedMay 10, 1967 and entitled Reaction Products of Multiaziridino CompoundsAnd Hydrogen Sulfide And Adhesive Compositions (now U.S. Pat. No.3,514,369).

BACKGROUND OF THE INVENTION Compounds containing the aziridino group,i.e.,

are known to be reactive with mercapto compounds (see Annalen 566, 2l0)according to the following general equation:

This basic reaction has been used to form amino alkyl thio benzenes (seeJ. Am. Chem. Soc. 80, 3458) by employing benzenethiol and similar arylmercaptans to react with aziridino compounds.

Instead of using monomeric, monofunctional reagents in this class ofreaction, polymeric-type multifunctional reagents have been used toprepared polymeric products by reaction of polyalkylene polys'ulfideprepolymers with polyfunctional aziridine ring containing monomers (seeU. S. Pat. No. 3,119,782). A variety of multiaziridino compounds aredisclosed as useable in preparing the polymeric materials.

Many varieties of multiaziridino compounds are known and, hence, arepotential reagents for use in reaction with mercapto compounds, e.g.,polyaziridinyl phosphate esters (U.S. Pat. No. 3,226,377),polyaziridinyl carbamates (U.S. Pat. No. 3,119,782), polyaziridinylphosphonic acids (U.S. Pat. No. 2,654,738) and a host of othermultiaziridino compounds (U.S. Pat. No. 3,260,702).

The present invention, by employing the general thiol aziridinyl groupreaction mentioned above in a new manner, i.e., through reaction of H,Swith specific multiaziridino monomeric compounds,.has been able tocreate new compounds containing secondary amino groups and thioether ormercapto groups which are of relatively high reactivity to othercompounds, e.g., epoxy groups. Mercapto groups in the new compounds arereactive with oxygen of the air making possible in situ formation ofdisulfide linkages useful in epoxy resin cross-linking operations.

OBJECTS A principal object of this invention is the provision of newcompounds containing secondary amino groups and thioether or mercaptogroups. Further objects include the provision of:

1. New methods of forming epoxy compound reactive adducts by reaction ofI-I,S with monomeric multiaziridino compounds.

2. New adhesive compositions comprising hydrogen sulfide adducts ofmultiaziridino compounds as active adhesive agents.

3. New highly effective cross-linkers for epoxide compounds.

4. New methods of creating laminations with metalto-metal bonding ofhigh strength.

5. New methods of compounding epoxy adhesives having good curingproperties which may be augmented by further air curing.

6 Improved forms of epoxide base paints and similar coatingcompositions.

Other objects and further scope of applicability of the presentinvention will become apparent from the detailed description givenhereinafter; it should be understood, however, that the detaileddescription and specific examples, while indicating preferredembodiments of the invention, are given by way of illustration only,since various changes and modifications within the spirit and scope ofthe invention will become apparent to those skilled in the art from thisdetailed description.

SUMMARY OF THE INVENTION These objects are accomplished, in part, by theproduction of new reaction products from hydrogen sulfide reacted withmultiaziridino compounds of the general formula: I

wherein the letters designate radicals as follows:

X is aryl, alkyl or R is hydrogen, hydrocarbon, Az or Y-Az, Az is (ill:

(in R;

R? is alkylene, R? is hydrogen or alkyl,

0 Y is o ti-; R O-t 3 or NHC-OR1-O.-C-

and

n is an integer selected from 2 and 3.

The invention also involves the discovery that highly effective adhesivecompositions may be prepared using these new reaction products as anactive adhesive agent. The reaction products are not adhesives per se,but may be considered as construction materials for adhesives.

As a preferred embodiment, new adhesives are created by combining suchreaction products with epoxy resins, advantageously, in a mixture of 5to 95 percent epoxy resin and 95 to 5 percent of thenew reactionproducts of hydrogen sulfide with the multiaziridino compounds of thetype as hereinbefore defined. Adhesives may be made from mixtures of twoor more of the new reaction products and/or two or more epoxy resins.Adhesives containing from 25 to percent epoxy resin and 75 to 25 percentof the new reaction products provide particularly useful properties.Additional agents such as fillers, pigments, dyes, accelerators,solvents and similar materials up to about 50 percent of the totalweight of the adhesive may be included.

A noteworthy feature of the invention is the discovery of the ability ofthe new reaction products to undergo air curing. Thus, mercapto groupswhich may exist in the reaction products can undergo cross-linking byexposure to oxygen of the air apparently by means of the formation ofdisulfide linkages. The new reaction products also contain NH groupswhich may react with epoxy groups enabling the reaction products tocross-link and cure epoxy resins, e.g., in adhesive compositions.Theair-curing feature, when utilized with epoxy resins, permits uniqueair curing epoxide base paints and other coating compositions to beformulated. The SH groups in the new reaction products may react withisocyanate terminated prepolymers to cure them or with activated doublebonds, e.g., as in acrylonitrile and acrylic esters.

The new reaction products may be advantageously formed to containaziridino groups, in addition to NH and SH groups giving products ofhigh chemical activity, e.g., useful in curing and cross-linking epoxyresins.

A further important finding of the invention is the good metal-to-metalbonding that can be attained with adhesive compositions containing thenew reaction products. As a result, the invention encompasses as newproducts laminated structures comprising a metalto-metal portion bondedtogether with an adhesive comprising the reaction products, e.g., 95 topercent of such reaction product and 5 to 95 percent of an epoxy resin.

EXAMPLES The following details of operations in accordance with theinvention and reported data illustrate the further principles andpractice of the invention to those skilled in the art. In these examplesand throughout the remaining specification and claims, all parts andpercentages are by weight and all temperatures are in degrees centigradeunless otherwise specified.

EXAMPLE 1 Nitrilo tris[ethyl(beta-N-ethylenimino)propionate] (235 parts)was dissolved in 156 parts dioxane in a glass reaction vessel. Hydrogensulfide was bubbled into the stirred solution until the temperature roseto 56 C., at which time the H S addition was adjusted so that theexotherm maintained 5055C. in the reaction mixture. The addition of H,Swas continued at this rate, for 2 hours, after which the exothermceased. The dioxane was removed by vacuum distillation to 80C. pottemperature at 5 mm. The residue, consisting of product represented bythe formula given below, amounted to 280 parts indicating 45 parts ofH,S had reacted.

Found Calculated Analysis: 1: SH 12.3 11.7 S 12.64 14.8 11 N 9.7 10.1

ln a subsequent operation, parts of Epon 828 epoxy resin and 75 parts ofthe reaction product of nitrilotris[ethy1(beta-Nethylenimino)propionate] and H 8 were thoroughly mixedtogether. Test coupons which consisted of l X 4 strips of phosphatedsteel had the resulting adhesive applied to them after which they wereplaced together with 0.5 in. overlap. The specimens were secured in aclamp consisting of two 1 inch square steel bars 6 inches in length heldtogether by bolts. The clamp nuts were tightened with a torque wrench to15 in. lbs. torque. The assembly was placed in a C. oven for 1 hour. Thespecimens were removed from the clamp and the shear adhesion value ofthe adhesive was obtained by pulling the specimens in an Instron testerat 0.05 in/min. crosshead speed. An average of the resulting testresults gave a value of 1,380 psi. for the shear adhesion.

The Epon 828 epoxy resin used as reported herein was a commerciallyavailable liquid product prepared in known manner for production of1,2-epoxide resins by reaction predominantly of bisphenol A with an excess of epichlorohydrin in the presence of sodium hydroxide to give aproduct with viscosity of about l0,00020,000 cps. at 23C. and an epoxyvalue (mols per kg.) of about 5-6.

EXAMPLE 2 Bis[(beta-N-ethylenimino)ethyl] benzene (216 parts) wasdissolved in 156 parts dioxane and heated to 45C. The heating wasstopped and H,S was bubbled through the stirred solution. The additionwas continued 4 hours at 5565C. The dioxane was removed by vacuumdistillation to C. pot temperature at 1 mm. The residue constituted thereaction product and amounted to 248 parts. This indicated that 32 partsof H,S had reacted.

Found Analysis: SH 10.3

In a subsequent operation, 100 parts of Epon 828 and 80 parts of thereaction product of bis[(beta-N- ethylenimino)ethyl] benzene and ms weremixed, cured and tested as in Example 1. An average shear adhesion of2,298 psi. was obtained.

EXAMPLE 3 Ethylenimine (89 parts) was cooled to l0-20C. in a glassreaction vessel and 162 parts of ethylene diacrylate were addeddropwise, with stirring, at 1020C. The mixture was left standingovernight and the excess ethylenimine was distilled out. To the ethylenebis(beta-N-ethylenimino)propionate formed was added 156 parts dioxaneand the solution was heated to 45C. Hydrogen sulfide was then bubbledthrough at such a rate as to maintain 50C. for 4 hours. The dioxane'wasthen distilled out at 80C.at 5 mm. The residue recovered amounted to 299parts indicating that the ll l l NCHzCIIzO C CHzCHrNCI-IzC III-Sreaction product was formed by the reaction of 51 parts of ms.

Found Analysis: Sl-l 14.55 S 16.47 N 8.7

In a subsequent operation, 100 parts of Epon 828 and 65 parts of thereaction product of ethylene bis(beta-N-ethylenimino)propionate and li swere mixed, cured and tested as in Example 1. An average shear adhesionof 2,120 psi. was obtained.

EXAMPLE 4 There was dissolved in 408 parts of dioxane 81 parts of2,4-tolyle'ne bis[(.beta-N-ethylenimino)propionoxy ethyl] urethane andthe solution was heated to 45-50 C. Hydrogen sulfide was bubbled in atthis temperature for 3% hours. The dioxane was distilled out undervacuum. The product was recovered as residue amounting to 102 partsindicating 21 parts of H S had reacted.

7 Found Analysis: SH 14.1 S 13.1 N 12.5

In a subsequent operation, 100 parts of Epon 828 and 50 parts of thereaction product of N,N(2,4- tolylene)bis [(beta-N-aziridino)propionoxyethyl] urethane'and H 8 were mixed, cured and tested as in Example 1. Anaverage shear adhesion of 1,526 psi. was obtained.

The aziridinourethane reagent used in the above example can be preparedby reacting 2 mols of hydroxy ethyl acrylate or similar hydroxyl alkylacrylate with one mol of 2,4-tolylene diisocyanate. Ethylenimine is thenreacted with the resulting ethylenic urethane by adding onto the doublebond to give thebis-aziridino compound according to the techniquedisclosed in copending application Ser. No. 577,804, filed Sept. 8,1966, now abandoned.

EXAMPLE 5 Bis[(beta-N-butylenimino)ethyl] benzene (68 parts) wasdissolved in 259 parts dioxane and heated to 80C. with stirring. Then, H8 was bubbled through at this temperature for 2 hours. The dioxane wasstripped out to 80 at 5 mm. The product was the residue recovered Iamounting to 72 parts.

Found Analysis: SH 3.2

k S 3.14 N 9.3

EXAMPLE 6 Four hundred parts of the sodium salt of 2,6-di-(N-ethyleniminomethyl)-4-methyl phenol in the form of a solution inisopropanol was prepared by first adding to a solution of 62 partsNaOl-l pellets in 400 parts of isopropanol, 167 parts of p-cresol withstirring to form sodium p-cresolate. The mixture was cooled to 30C. and139 parts of ethylenimine were added. At a temperature between 3035C.,262 parts of 37 percent aqueous formaldehyde was added dropwise withstirring. After the formaldehyde addition was completed, the reactionmixture was heated to 50C. for 2 hours.

The resulting clear solution was stirred in a glass reaction vessel andH 8 was bubbled through for 3% hours, with a temperature rise to C. Twophases were formed. The lower rust brown phase was dissolved in 450parts CHCl The solution was washed three times with 300 parts hot water.The CHCl solution was distilled under high vacuum up to C. 80 parts of aviscous brown residue were recovered. Analysis: 7.7% nitrogen In asubsequent operation, 100 parts of Epon 828 and 75 parts of the reactionproduct of the Na salt of 2,6-di-(N-ethyleniminomethyl)-4-methyl phenoland Pi s were mixed, cured and tested as in Example 1. An average shearadhesion of 1,795 psi. was obtained.

The aziridinophenol reagent used in this example may be prepared byreaction of ethylenimine with 2,6- dimethylol-4-methyl phenol in thepresence of sodium carbonate under anhydrous conditions at refluxconditions at atmospheric pressure.

EXAMPLE 7 The following adhesive formulation was mixed and tested asdescribed below:

75 parts Epon 828 25 parts DEN 438 (epoxidized Novolac resin) 65 partsreaction product of ethylene bis(beta-N- ethylenimino propionate) and H8.

Coupons were prepared from a 1 inch X 4 inch strip of phosphated steeland a 1 inch X 4 inches strip of fiberglass reinforced polyester, thetest surface of which had been lightly sanded and wiped'with methylethyl ketone. The adhesive was applied to thetest surfaces of thecoupons in a thincoat and the members were placed together with onlycontact pressure. The member overlap was one-half inch, giving it sq.in. test area. The specimen was assembled with the test portion in thecenter of the work coil of a 0.5 kilowatt induction heater. The curetime in the induction heater was 10 seconds. The specimens were thenpulled by an Instron tester at 0.05 in./min. cross-head speed. Theaverage shear adhesion was 2,230 psi. with primarily failure of thepolyester laminate.

DISCUSSION OF DETAILS The amounts of the reagents employed in producingcompositions in accordance with this invention are not narrowlycritical. The amount of the multiaziridino compound employed can be suchthat there is present is greater than 1:1, the resulting products aregenerally increased in complexity and contain a plurality of moietiesfrom the multiaziridino compound. Mixtures of multiaziridino compoundscan be used in such cases and mixed products obtained. As such ratioincreases above 1:1, e.g., 2:1 to :1, the products tend to be polymericcomprising a plurality of moieties of the multiaziridino compound joinedby S linkages.

Within the class of multiaziridino compounds useable in the invention,there are two useful specific groups of polyaziridinyl hydrocarbons,namely, compounds having the formula:

wherein A is a four to six carbon atom saturated or unsaturatedaliphatic radical, and

R is hydrogen or one to three carbon atom alkyl. And compounds havingthe formula:

UlIR

wherein R is one to three carbon alkyl, and B is an alkylene radicalcontaining one to six carbon atoms.

Specific examples of multiaziridino alkanes or alkenes which may beadvantageously used include:

l,4-di-(N-ethylenimino)butane 1,S-di-(N-ethylenimino)pentanel,4-di-(N-butylenimino)butene-2 l,6-di-(N-ethylenimino)hexanel,S-di-(N-ethylenimino)-3-(N-ethyleniminomethyl)- pentane3-methylene-1,S-di-(N-ethylenimino)pentanel,4-di-(2-methyl,3-amylaziridino)butane. With respect to multiaziridinomethylene benzenes,

suitable examples of compounds include:p-bis-(N-butyleniminomethyl)benzene p-bis-(N-ethyleniminomethyl)benzeneo-bis-.(N-butyleniminomethyl)benzenep-bis-(N-propyleniminomethyl)benzene p-bis-(2,3dimethylaziridinomethyl)benzenem-bis-(2-methyl,3amylaziridinomethyl)benzene1,2,4-tris-(N-butyleniminomethyl)benzene l,3-bis-( N-butyleniminomethyl)naphthalene 1,2,4,6-tetra-(n-ethyleniminomethyl)benzenel,2,8-tris-(N-propyleniminomethyl )naphthalene. Illustrative ofadditional multiaziridinyl aryl compounds which can be employed inproducing the compositions of this invention are, for example, theortho,

meta or para isomers of:

bis-(N-ethyleniminoethyl)benzene bis-(N-ethyleniminoisopropyl)benzenebis-(N-propyleniminoethyl)benzene bis-(N-propyleniminoisopropyl)benzenebis-(N-butyleniminoethyl)benzene bis-(N-butyleniminoisopropyl)benzene aswell as:

bis-(N-ethyleniminoethyl)naphthalenesbis-(N-ethyleniminoisopropyl)naphthalenesbis-(N-butyleniminoethyl)naphthalenesbis-(N-ethyleniminoethyl)biphenyls; and the like. Examples of thearomatic nuclei which X represents 1 in the general formula givenhereinbefore include the di-, tri-, and tetra-valent groups derived frombenzene, toluene, ethyl benzene, naphthalene, anthracene, diphenyl,phenanthrene, terphenyl, xylene and their alkyl substituted derivativesand the like. It is understood, of course, the alkyl substitutedaromatic compounds such as mesitylene (trimethyl benzene) could only bea dior tri-valent group, and durene (tetramethyl benzene) could only bedivalent.

Another class of multiaziridino compounds advantageously used in theinvention are aziridinocarboxylic acid esters as disclosed in copendingapplication Ser. No. 577,804, filed Sept. 8, 1966, now abandoned, thedisclosure of which is incorporated herein by reference. Such compoundsuseable herein may be represented by the following formula:

wherein n is the integer 2 or 3, R is a hydrogen or hydrocarbon radicalcontaining one to 18 carbon atoms, 1

R is a bivalent hydrocarbon radical, especially such radical containingone to six carbon atoms, and

Z is a polyvalent hydrocarbon radical, especially such radicalcontaining one to six carbon atoms.

Representative examples of aziridinocarboxylic acid esters of this classinclude:

1,3-propylene propylenimino)propionate ethylenebis-(beta-N-ethylenimino)propionate l ,6-hexylenebis-(beta-N-propylenimino)propionate 1,2,3-propylene tris-(alpha-N-ethylenimino )acetate 1 ,3-hexylene bis-(8N-ethylenimino)caprylate l ,Z-propylene bis-( beta-N- propylenimino)propionate 1 ,2-propylene ethylenimino)propionate ethylenebis-(p-N-ethylenimino)benzoate ethylenebis-(alpha-N-ethylenimino)stearate. In the production of adhesivesincorporating the new reaction products, various known adhesivematerials may be used to advantage. Particularly suitable arebis-(beta-N- bis-(beta-N-tetramethyl epoxy resins, polyurethanes, andother adhesivematerials reactive with an active hydrogen compound. Awide variety of epoxy resins or ethoxyline materials are available forthis use, e.g., see U. S. Pat. Nos. 2,863,853; 2,890,196 and 2,890,204.

Useable products can be formed by mixtures which consist solely of thereaction product of the multiaziridine and hydrogen sulfide. Mixtures oftwo or more of these products may advantageously be employed. Also,additional compounding agents commonly employed in rubber and polymerfabrication may be incorporated. Such added materials which maytypically constitute lpercent and preferably 5-50 percent of the totalcomposition including the multiaziridine reaction product. Examples ofsuch additional materials include fillers or pigments, e.g., carbonblack, chalk, zinc oxide, barium sulfate, titanium dioxide, chromiumoxide and the like; fire retardants, e.g., polychloroaromatic compounds,zinc borate, antimony sulfides and the like; light stabilizers,antioxidants; plasticizers, e.g., dialkyl phthalates, fatty acid esters,etc.; heat stabilizers, mold release lubricants and the like.

CONCLUSION wherein the letters designate radicals as follows:

X is aryl having one to four aromatic rings which may or may not besubstituted with lower alkyl groups, Az is n is an integer selected from2 and 3. 2. A compound as claimed in claim 1 wherein the radicals R andR contain up to six carbon atoms.

2. A compound as claimed in claim 1 wherein the radicals R2 and R3contain up to six carbon atoms.